1. Field of the Invention
This invention relates to telephone equipment, and more particularly to user terminals that communicate with a telephone network by way of a wireless interface, using radio or other means.
2. Related Art
As is well known, such systems allow the user to take the terminal from one place to another and remain in contact with the network, a facility generally referred to as “mobility”. However, mobility facilities can also be provided on a fixed, or “wired” network by arranging the system such that the user may access the network using any one of its wired network termination points.
To perform mobility services in any network, the network must be aware of the identity of the user when contact is first made. In mobile networks according to standards such as GSM, the identity of the user is stored on a smart card (SIM Card) in the terminal, and this communicates with the network via the terminal. The user is thus identified as currently using a specified mobile terminal, which is in communication with the network through a specified fixed radio base station. In a fixed-wire network, the user identification is either done by keypad entry (protected by PIN numbers), or by a voice-controlled system that the user dials into, or by physically inserting a card or other identification means into the wired terminal.
For a number of reasons, users wish to have the choice of whether to use a wireless user terminal or a fixed-wire terminal. Wireless terminals can be used in situations where no fixed terminal is available, for example in a moving vehicle, but many users prefer to use fixed terminals when they are available. Mobile terminals generally have higher call tariffs, are dependent on battery power, and have ergonomic constraints caused by their limited size, such as the number and size of keys on the keypad. Indeed, some terminal types, in particular facsimile machines, are too bulky to be suitable for use as mobile terminals, and others, such as high bandwidth devices like video systems, are unsuitable for the relatively low bandwidth available over a cellular radio connection. Many users therefore have both a fixed line identity (which may allow mobility between fixed line terminals) and a cellular identity.
It is desirable to have a uniform means by which a user can be identified to the network through any type of terminal. It would be possible to devise fixed-wire terminals which accept GSM smart cards (SIMs). However, these cards have to be very small to allow their use in portable mobile terminals. The frequent transfer of such cards from one terminal to another is inconvenient, and there is a serious risk of losing or damaging the cards in such transfers.
The proposed short-range radio interface system developed under the Trade Mark “Bluetooth” is designed for interconnecting such items as mobile telephones and laptop computers, or printers and PCs, and is described in Ericsson Review No 3, 1998, Jaap Haartsen, “BLUETOOTH—The universal radio interface for ad hoc, wireless connectivity”. It is a radio interface using the 2.45 GHz frequency band designed to allow suitably equipped portable electronic devices to connect and communicate wirelessly via short-range ad hoc networks. Such networks are known, in that article and also in this specification as “piconets”. Each unit can simultaneously communicate with several other units. The system allows wireless communication between mobile telephones, computers, headsets and any other device suitably equipped. However, most existing telephone terminal equipment is not so equipped.
Existing piconet connections for mobile telephones are provided to allow interaction between a remote user interface and the user-controlled parts of the mobile interface, for example to allow hands-free operation or downloading of data to the telephone for onward transmission.